Observations from Andesite Ridge

Location Name: 
Andesite Ridge
Region: 
Donner Summit Area
Date and time of observation: 
Tue, 03/05/2013 - 15:30
Location Map: 
United States
39° 20' 58.1496" N, 120° 21' 56.9232" W
See map: Google Maps
US


Red Flags: 
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Minor wind loaded occurred last night along the near and above treeline ridgelines on Andesite Ridge. Snow transport had stopped by this afternoon. The resulting wind slabs only measured 1-3 inches thick. Above these wind slabs and on sheltered aspects a thin breakable melt freeze crust had formed due to above freezing air temperatures and the blanket of clouds over the area. This crust only existed up to about 7900 ft. Below the thin wind packed layer, softer lighter snow existed on top of the old rain crust. Snowpit tests, ski cuts on test slopes, and general observations all indicated that fractures were unlikely to travel through either the layer of lighter snow below the wind slab or the layers of snow around the crust. One ski cut on a steep NE facing test slope did release some small roller balls.

Photo 1: Roller balls released on a small NE facing slope at about 8000 ft.

Photo 2: A pillar of ice left over formed as rain draining through the snowpack refroze.

Snowpit: Data taken at the coordinates attached to this observation.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Strong
Precipitation: 
Air temperature trend: 
Cooling
Wind Direction: 
Southwest
Accumulation rate: 
More detailed information about the weather: 

Even though the winds were strong enough to transport snow, a melt freeze crust on the surface in this area was preventing any significant wind transport.